Stacking device



F. J. HOHL STAGKING DEVICE Oct. 17, 1.967

4 Sheets-Sheet 1 FIG.

FIG 3 fo cao o Has F INVENTOR. Fa RANK J. HOHL 6ewru ATTORNEYS Oct. 17, 1967 Filed May 4, 1964 F. J. HOHL STACKING DEVICE 4 Sheets-Sheet 2 INVENTOR. FRANK J. HOHL 2M +gaa w ATTORNEYS 4 Sheets-Sheet (S F. J. HOHL STACKING DEVICE 8 ET, m9 mo. 2 No. 1 .wm m 5 mm wm mm o9 g mm n INVENTOR. FRANK J. HOHL ATTORNEYS Oct. 17, 1967 Filed May 4, 1964 F. J. HOHL STACKING DEVICE Oct. 17, 1967 4 Sheets-Sheet 4 Filed May 4, 1964 INVENTOR. FRANK J. HOHL L J Il ATTORNEYS United States Patent 3,347,396 STACKING DEVICE Frank J. Hohl, Snyder, N.Y., assiguor to Hohl Machine 81 Conveyor Co. Inc., Buffalo, N.Y. Filed May 4, 1964, Ser. No. 364,435 18 Claims. (Cl. 2146) This invention relates generally to the materials handling art, and more specifically to a new and useful automatic stacking machine particularly adapted for stacking corrugated sheets of magnetic material although its utility is not limited thereto.

A primary object of my invention is to provide a machine capable of stacking corrugated and other sheet material automatically, precisely and at high speed.

Sheet material stacking devices, of the type to which this invention relates, customarily rely upon end stops to limit forward travel of the sheets and define the stacking position thereof. This poses a problem, because the forces involved are substantial. The end stops require shock absorbers, and the end stops must be moved as necessary to accommodate sheets of different lengths. This requires careful scheduling and programming.

Accordingly, it is also an object of .my invention to provide a trailing end stacking machine, avoiding such forward end stops and the problems incident thereto.

Another object of my invention is to provide a stacking machine capable of automatic lateral olfset stacking of successive sets of corrugated and other sheet material.

Still another object of my invention .is to provide a stacking machine capable of automatic longitudinal offset stacking of successive sets of sheet material.

In addition, an important object of my invention is to provide an automatic stacking machine for corrugated and other sheet material operable to convey reject material through and beyond the stacking area.

A device for stacking sheet material constructed in accordance with my invention is characterized, in one aspect thereof, by the provision of a runout conveyor having at least two rolls adapted to receive a sheet of magnetic material thereagainst on the underside thereof, means for delivering a sheet of magnetic material along the underside of the conveyor rolls in a direction generally normal to the axes of rotation thereof, magnetic holding means for magnetically holding a sheet of magnetic material against the underside of the runout conveyor as the material is delivered therealong, and means forselectively causing the magnetic holding means to release the magnetic sheet material being held thereby.

In another aspect thereof, a device for stacking sheet material constructed in accordance with my invention is characterized by the provision of a runout conveyor having at least two rolls, means for delivering sheet material along a predetermined path, and means for moving the runout conveyor between a stacking position wherein the conveyor rolls are immediately above the sheet material path for receiving the sheet material along the underside of the rolls, and a reject position wherein the conveyor rolls are immediately below the material path for receiving the sheet material along the upper side of the rolls.

In another aspect thereof, a sheet material stacking device constructed in accordance with my invention is characterized by the provision of a runout conveyor having at least two rolls, means for delivering sheet material along a predetermined path, means for moving the rundut conveyor between a stacking position; wherein the conveyor rolls are immediately above the path to receive sheet material along the underside of the rolls and a reject position wherein the conveyor rolls are positioned immediately below the material path for receiving sheet material along the upper side of the rolls, means for releasably about on line 7-7 of FIG.

holding sheet material against the underside of the runout conveyor rolls when the runout conveyor is in its stacking position, and means urging the rolls about their axes in a direction resisting movement of sheet material along the underside thereof, thereby facilitating rolling movement of sheet material along the upper sides of the rolls when the conveyor is in its reject position.

In still another aspect thereof, a sheet material stacking device constructed in accordance with my invention is characterized by the provision of at least two rolls adapted to receive sheet material against the underside thereof, means for delivering successive sheets of material along the underside of the rolls in a direction generally normal to the axes thereof, means for holding successive sheets of material against the underside of the rolls as the material is delivered therealong and then releasing the same, means for supporting the released sheets, and trailing end positioning means movable against the trailing end of the released sheet for endwise positioning thereof.

The foregong and other objects, advantages and characterizing features of a stacking machine of my invention will become clearly apparent from the ensuing detailed description of certain illustrative embodiments thereof, considered in conjunction with the accompanying drawings wherein like reference numerals denote like parts throughout the various views and wherein:

FIGS. 1 through 5 comprise schematic illustrations depicting the general arrangement and mode of operation of a stacking machine of my invention;

FIG. 6 is a longitudinal elevational view of a stacking machine of my invention, certain parts being shown in section, and parts being broken away for ease of illustration;

FIG. 7 is a transverse sectional view thereof, taken 6, certain parts being omitted and others broken away for clarity and ease of illustration;

FIG. 8 is a fragmentary transverse sectional view, taken about on line 8-8 of FIG. 6 and with parts omitted and others broken away for clarity and ease of illustration;

FIG. 9 is an inlet end elevational View thereof;

FIG. 10 is a top plan view of an alternate trailing end positioning mechanism, parts being broken away for ease of illustration; and

FIGS. 11 and 12 are sectional and end elevational views thereof, being taken about on lines 11-11 and 12-I2, respectively, of FIG. 10.

A stacking mechanism of my invention, and its mode of operation, are depicted schematically in FIGS. l-5. The mechanism is shown as comprising a runout conveyor having a series of idler rolls 1 spaced apart in parallel relation, and a series of permanent magnets 2 interposed there between. Sheet material 3 is shown being delivered to the runout conveyor from a forming machine or other device, indicated generally at 4, through a shear 5 and past a photocell 6. The runout conveyor 1, 2 normally is positioned to receive material 3 against the underside of rolls 1, as shown in FIG. 1, but it can be positioned to by-pass reject material, as shown in FIG. 5.

Operation of shear 5 actuates a switch 7, causing a pair of squeeze rolls 8 to move into squeezing relation to the sheared sheet 3 on opposite sides thereof (FIG. 2). Rolls 8 initially are rotated at high speed and thereby take the sheared sheet away from the following sheet material, delivering it along the underside of rolls 1 in the stacking position of the runout conveyor. When the trailing end of the sheared sheet passes beyond photocell 6, rolls 8 are driven at a lower speed, and a timer, not shown, is actuated, whereupon three functions are performed. First, rolls 8 open and rotate at high speed. Second, the magnets 2 are raised (FIG. 3), striking a switch, not shown, controlling their return. Raising of magnets 2 weakens their magnetic hold on the sheet 3, which there- 3 upon is released and drops onto regular supporting arms (FIG. 4). Third, a positioner 11 is moved forward, for trailing end positioning of the stacked sheet on arms 10.

Arms 19 are progressively lowered as successive sheets are stacked thereon, as indicated in broken lines in FIG. I, eventually depositing the stacked sheets on a take-out conveyor 12.

In the illustrated embodiment, the stacking mechanism of my invention includes a supporting framework having a pair of end members 13 at the inlet end thereof, and a pair of opposite end members 14. Members 13 and 14 are joined by side rail members 15 extending lengthwise of the mechanism, on opposite sides thereof. The side rail members are joined at spaced intervals by temporary support arm members, to be described, and at the inlet end by cross member 43.

The runout rolls 1 are journalled at their opposite ends in suitable bearings, not shown, carried by side rails 17 of a roll supporting framework having cross rails 18 (FIG. 7) to comprise the runout conveyor.

The runout conveyor thus described is suspended by cables or chains 19 (FIGS. 7 and 8) trained over drums 20 mounted on angle members 21. The drums 20 on each side of the runout conveyor are joined by a shaft 22, for movement in unison, and the paired drums on opposite sides of the conveyor are joined by cross cables 23 for movement in unison to lift and lower the runout conveyor. The motors for such lifting and lowering comprise pneumatic cylinders 24 pivotally mounted on members 21. The piston rods 25 of cylinders 24 are pivoted to arms 26 secured to one of the shafts 22, for rotating it in opposite directions to lift and lower the runout conveyor. In this way, the runout conveyor can be moved between the stacking position of FIGS. 1-4 and 68, and the reject position of FIG. 5.

Permanent magnets 2 can be of any suitable type, such as the magnetic rails sold by Eric Manufacturing Co., Erie, Pennsylvania, under the name Magna-Rails. They are mounted in a frame having side rail members 27 (FIG. 7), the magnet frame being suspended by cables or chains 29 from drums 30 mounted on the members 18 of the runout conveyor. Here again, the drums 30 on each side of the magnet frame are connected by a shaft 31, and the paired drums on opposite sides are connected by a cable 32, for movement in unison. Pneumatic cylinder motors 33 are pivotally mounted on members 18 and have piston rods 34 pivotally connected to arms 35 projecting from one of the shafts 31, for raising and lowering the magnet frame.

In this way, magnets 2 can be raised relative to the runout conveyor, as indicated in FIG. 3, to release the sheet for stacking, and then lowered to their holding position shown in FIGS. 1 and 2. Also, the magnets will be raised and lowered with the runout conveyor, as the latter is moved between stacking and reject positions.

It will be noted that magnets 2 are positioned in vertically spaced relation above the underside of rolls 1, even in the holding position thereof. There is no physical contact between magnets 2 and sheets 3, thereby avoiding sliding friction therebetween. Instead, the sheets 3 roll along the underside of rolls 1, being held thereagainst by the force of magnetic attraction of the magnets. When the magnets 2 are raised, relative to rolls 1, this force is reduced below the level required to hold sheet 3 against rolls 1, and the sheet thereby is released.

Squeeze rolls 8 comprise a cylindrical lower roll covered with rubber or other friction producing material, and an upper roll consisting of spaced wheels 40, also covered with a friction producing material and adapted to engage the sheet material 3 between adjacent corrugations. Where flat material is used, a pair of cylindrical rolls 8 will be provided. In the illustrated embodiment, the upper roll only is raised and lowered, for opening and closing the rolls, this being accomplished by motors comprising a pair of pneumatic cylinders 41 having their piston rods connected to a bracket 42, in which the upper roll is journaled. Cylinders 41 are pivoted on cross frame member 43. Guide yokes 42' are carried by bracket 42 and have sliding engagement with member 43.

The lower roll 8 is driven by an hydraulic motor 44 through a speed reducer 45 and a belt or chain drive 46. Motor 44 and reducer 45 are mounted on a bracket 44' secured at its ends to inner side frame members 16, in which the lower roll 8 is journaled. While such inner frame could be dispensed with, it permits the outer inlet side members 13 to act as guards. Obviously, the upright frame members will be fastened to the floor. The upper roll is driven by the lower roll when the two rolls are in pinching engagement with sheet material therebetween.

It is a particular feature of my invention that I avoid any necessity for front end stops. Instead, the sheets are stopped by the runout conveyor itself, as will be more fully described hereafter, and I provide trailing end positioning of the stacked sheets. In one form of positioner, a bracket 47 is carried by bracket 48 mounted on one end of guide rods 49 journaled for reciprocation and actuated by air cylinder motor 50. The opposite ends of guide rods 49 are connected to a flange 51 movable therewith.

Motor is mounted on bracket 49 carried by cross frame member 48'.

Multiple fingers 52 having shoulders 53 are carried by bracket 47, for being extended and retracted by air motor 56. As each sheet 3 is released from. the runout conveyor to drop onto the supporting arms 10, the trailing end of the sheet falls on fingers 52. There is very little clearance between the runout conveyor and the supporting arms, whereby as the fingers 52 are advanced the shoulders 53 thereof will engage the trailing end of the sheet, and thereby push the sheet into predetermined stacking position, as determined by engagement of the flange 51 against the end of housing 54. Retraction of the fingers 52 permits the aligned sheet to fall onto the stack of sheets therebelow.

Where it is desired to stagger sheets, in endwise relation, a stop 55 is moved outwardly by an air motor in housing 54, to project beyond the end of housing 54 in the path of flange 51, thereby defining the end limit of a foreshortened path of travel for the flange 51 and rods 49.

An alternate trailing end stacking arrangement is shown in FIGS. 1012. In this arrangement, a carriage is mounted on wheels 61 adapted to move along tracks 62. Such movement is provided by an air motor 63 mounted on a cross bracket 63' at the inlet end and having a piston rod 64 connected to a bracket 65 fixed to the carriage 60. Carriage 60 supports a table 66 adapted to receive the sheet material 3 thereon, the table being slightly inclined, downwardly and forwardly, to match the inclination of the sheet material when its forward, leading end portion is resting on arms 10, or on the stack of sheets, and its rearward, trailing end portion is resting on the table 66. The forward end 67 of table 66 defines the desired trailing end position of the sheet, for stacking purposes.

Successive sheets 3 are pushed off table 66 at the end 67 thereof by one or the other of pushers 68 each having a leg yoke 69 pivoted intermediate its end to a bearing 70 slidable along rods or ways 71. Arms 72 extend from one end of legs 69, and in one position thereof project upwardly above the table 66. Motors in the form of air actuated cylinders 73 are supported on the frame by means, not shown, and have their piston rods 74 pivotally connected at 75 to the lower ends of legs 69.

One pusher 68 is retracted, while the other pusher is extended, thereby -providing for alternating operation thereof. The pusher being extended automatically is pivoted to the raised, projecting position shown, because its piston rod 74 pushes its leg 69 in a counterclockwise direction, against a stop shoulder 76. The pusher being retracted is pivoted clockwise by its rod 74, against stop shoulder 77, to lower its arm 72 out of sheet material engaging position.

When it is desired to offset sheets, cylinder 68 is actuated to move carriage 60, thereby repositioning the table end 67 to define the new end position.

Thus, with both forms of trailing end positioner, front end stops are omitted and the sheets are stacked and positioned irrespective of length and without need for programming adjustments to accommodate sheets of different lengths. The positioner of FIGS. 1042, with its alternating pushers and relatively longer bed or table 66 is faster acting and less critical, and thereby is preferred.

With the omission of end stops, some means must be provided to insure that the sheets being run out on the conveyor stop before they reach the end of the conveyor or go beyond the stacking position. The idler roll bearings initially can be made sufficiently tight so that the friction thereof will slow down and stop the sheets. However, as the bearings are run in they loosen, and no longer are adequate for this purpose.

Therefore, it is a further feature of my invention that I provide means operable to insure timely stopping of the sheet, without resort to end stops. In accordance with the illustrated embodiment of my invention, this is accomplished through an adaptation of a live roller conveyor of the typeset forth in my Patent 3,040,872, issued June 26, 1962.

Referring now to FIGS. 6-8 of the accompanying drawing, there is provided a belt 80 extending around an idler pulley 81 and a drive pulley 82 carried by the runout conveyor. The lower flight of belt 80 is in frictional en gagement with the upper side of runout rolls 1, along one side of the frame. Belt 80 comprises rubber or the like to provide a friction producing surface against rolls 1. To increase the frictional engagement therebetween, a plurality of weights 83 are superposed on the lower flight of the belt, to hold it in frictional engagement with the roll 1. Restraining fingers 84 engaging posts 85 on the weights restrain them against movement with the belt, while enabling relative vertical movement thereof, and each weight member spans no more than two rolls. A single elongated tie member can be used, instead of individual fingers, as disclosed in my said patent. The upper flight of belt 80 simply. returns along the upper side of an inverted channel housing 86 having an upstanding wall to confine the belt. A motor 87, carried by the runout conveyor, drives belt 80, in a direction to rotate rolls 1 opposite to the direction of rotation imparted thereto by the sheet material 3.

Therefore, as the sheet material 3 rolls along the underside of roll 1, its progress is slowed by the reverse rotational force imparted by the belt 80. Through the appropriate selection of weights 83 this restraining force can be regulated, to stop the sheet 3 against the underside of the runout conveyor within the limits required for the tail end positioning means.

Thus, with my invention any need for front end stops, to stop the sheet material, is eliminated. Belt 80 and/or weights 83 can be provided with an antifriction surface, the weights can be backed u and the weights can be carried by belt 80, all as more fully described in my aforesaid patent to which reference is hereby made for such details.

Of particular interest is the arrangement for bypassing reject material and conveying it away from the stacking area. This is accomplished as follows. When a sheet is to be rejected, the runout conveyor is lowered by motors 24, until the upper level of idler rolls 1 lies along the path of the sheet material 3 (FIG. 5). This can be done automatically. The sheet material then rolls along the top of the rolls 1, and it will be noted that the slowdown belt 80 now operates to drive the rejected material along and beyond the runout conveyor. The direction of rotation of the runout conveyor rolls 1 by belt 80 is such that, whereas in the norm-a1, stacking position of the d runout conveyor it functions to slow down the sheet for stacking purposes, in the reject position it drives the rolls in a direction conveying the rejected material through the runout conveyor beyond the stacking position.

Thus, with my invention reject material is disposed of without shutting down, and without interfering with the stacking operation other than to momentarily shift position to reject the sheet. Belt and its associated parts move with the runout conveyor which is returned to stacking position, automatically if desired, as soon as the reject material has passed through.

The supporting arms 10 are mounted on shafts slidable through bearings 91 carried by cross member 92 of take-out conveyor 12. Arm shafts 91) are connected at their lower ends by channel members 117, and are lifted and lowered by drive shaft 99' which is rotated by a suitable motor, not shown. Shaft 99 carries drum 99 about which is trained a cable 116 connected at one end to drum 99 and at its other end to member 117. Rotation of drum 99 in opposite directions thereby raises and lowers arms 10.

Where it is desired to laterally offset the stacked sheets, each arm 10 is provided with a shoe portion 97 engaging over a rail 98 carried by the shafts 90. Rail 98 carries rollers 107 engaging plates 108 carried by shoe 97, for rolling support of the latter. A drum 160 is carried by a bracket 101 on the rail 98.

A supporting frame including cross member 94 and inverted U-shaped end members 94' is connected to member 117 by channel members 117', for being raised and lowered with arms 10. An air cylinder motor 93 has a clevis connection to supporting member 94, and its piston rod 95 is connected to an arm 96 on jack shaft 106' journaled in bearings carried by end members 94'. A pair of cables 98' train around and are connected at one end to a drive pulley 102 on shaft 96. Cables 98' also train around drum 100, with their other ends being connected to brackets 104 and 105 on shoe 97. Shaft. 96 is adapted to be rotated by cylinder 93, through gear ran on jack shaft 1% which engages gear 103 on shaft 96'. Rotation of shaft 96' in opposite directions will wind and unwind cables 98' to shift shoes 97 back and forth on their rails 98. In this way, the sheets carried by the shoes 97 of arms 10 can be laterally offset, as may be desired, this being under control of the program circuit not shown.

The downward indexing of support arms 10 is controlled by photocell 9, which causes the arms to be lowered each time the stack of sheets reaches a predetermined level as detected by the photocell. When a predetermined number of sheets have been stacked on the supporting arms 10, an end of bundle signal is received from the mill program console, not shown, at the same time as the shear signal is received. Arms 10 thereupon bottom, and the stack of sheets is deposited on the take-out conveyor 12 which extends at right angles to the runout conveyor, and which can be of conventional construction. The stacking operation continues, however, because temporary support arms are shifted inwardly below the runout conveyor, at the level of arms 10 in their uppermost position. Temporary arms 110 are carried by brackets 111 depending from a carriage 112 movable along tracks 113 on V-grooved wheels 114. Tracks 113 are simple right angles, carried by I-beams 21. Arms 110 are moved by air cylinder motors 115 having piston rods 116 connected to carriages 112. The temporary arms 110 do not lower, since they are used for such a brief instant of time. They are positioned between the regular support arms 10. After the stack of sheets has been transferred to take-out conveyor 12, arms 10 are raised to a point above arms 11d, whereby they pick up the sheets stacked on the temporary arms 110, which latter then are retracted.

It will be appreciated that numerous support arms 10 and 110 can be provided, the number of which will vary with the length of the runout conveyor. Also, it will be appreciated that the various programming and control circuits are conventional, per se, and of a type readily apparent to those skilled in the art.

Accordingly, it is seen that my invention fully accomplishes its intended objects. Sheets of different lengths can be accommodated, without necessity for adjustment or reprogramming of the machine, and the machine is operable with a minimum of operator attention. It is capable of high speed, precision operation, and need not be shut down to remove reject material.

While I have disclosed and described in detail only two embodiments of my invention, that has been done by way of illustration, and not necessarily by way of limitation, it being intended to include within the scope of the appended claims those variations and modifications which will naturally occur to those skilled in the art.

Having fully disclosed and completely described my invention, and its mode of operation, what I claim as new 1. A device for stacking sheets of magnetic material comprising a series of rolls adapted to receive successive sheets therealong against the underside thereof, means for delivering successive sheets of magnetic material along said series of rolls on the underside thereof in a direction generally normal to the axes of rotation of said rolls, magnet means positioned between adjacent ones of said rolls and operable to hold magnetic sheet material against said rolls through magnetic attraction of the sheet to the magnet means independent of the rolls, and means for raising said magnet means relative to said rolls for releasing a sheet from the magnetic hold of said magnet means to drop from said series of rolls wherein said magnet means are maintained out of physical contact with a sheet held against the underside of said rolls.

2. A device for stacking sheet material comprising a run-out conveyor having at least two rolls, means for delivering sheet material along a predetermined path, means for moving said run-out conveyor between a stacking position with said rolls immediately above said path to receve such sheet material along the underside of said rolls and a reject position with said rolls immediately below said path to receive such sheet material along the upper side of said rolls, and means for releasably holding sheet material against the underside of said rolls when said conveyor is in said stacking position.

3. A device as in claim 2, together with means urging said rolls about their axes in a direction resisting movement of sheet material along the underside thereof.

4. A device as in claim 2 for stacking sheets of magnetic material wherein said last-named means comprise magnet means positioned adjacent said rolls and operable to hold magnetic sheet material against the underside of said rolls through magnetic attraction, and means for raising said magnet means relative to said rolls to release the sheet material.

5. A device for stacking sheet material comprising a conveyor having at least two rolls adapted to receive a sheet of material against the underside thereof, means for delivering successive sheets of material along the underside of said rolls in a directon generally normal to the axes thereof, magnet means releasably holding successive sheets of material against the underside of said rolls as the sheets are delivered therealong, drive means urging at least certain of said rolls in a rotational direction opposing the travel of sheet material along the underside thereof, thereby to slow down and stop sheet material delivered along the underside of said rolls, and means for raising said magnet means relative to said rolls to release such sheet material.

6. A device for stacking sheets of magnetic material compirsing a series of rolls adapted to receive successive sheets of magnetic material therealong against the underside of said rolls, means for delivering successive sheets of magnetic material along the underside of said series of rolls in a direction generally normal to the axes of rotation thereof, permanent magnets positioned between said rolls for holding magnetic sheet material against the underside of said rolls as the same is delivered therealong, and means for raising said magnets relative to said rolls to release such sheet material, said last-named means including drum means, cable means suspending said magnets from said drum means, and motor means operable to rotate said drum means.

7. A device for stacking sheet material comprising a conveyor having at least two rolls, means for delivering sheet material along a predetermined path generally normal to said rolls, said conveyor having a stacking position wherein said rolls are positioned to receive such sheet material against the underside thereof and a reject position wherein said rolls are positioned to receive such sheet material against the upper side thereof, means for retaining the sheet material against the underside of said rolls, and means for moving said conveyor between said positions including drum means, cable means suspending said conveyor from said drum means, and motor means for rotating said drum means to wind and unwind said cable means.

8. A device for stacking sheets of magnetic material comprising a series of generally parallel spaced rolls, supporting arms movable between a raised position adjacent said series of rolls and a lowered position, means for delivering successive sheets of magnetic material along the underside of said series of rolls in a direction generally normal to the axes of rotation of said rolls, magnet means positioned adjacent said rolls and operable to hold successive sheets of magnetic material against the underside of said rolls as the same are delivered along said series of rolls, means operable to release the hold of said magnet means on successive sheets of material being held thereby against the underside of said rolls, thereby enabling successive sheets to drop from said rolls onto said supporting arms, means for progressively lowering said arms as successive sheets are stacked thereon, and positioning means including means for temporarily supporting the trailing ends of successive sheets after actuation of said release means, and means engageable against the trailing end portion of a temporarily supported sheet and sliding the same off said temporary support means for endwise positioning of the sheets prior to disposing the sheets in stacked relation.

9. A device as in claim 8, wherein said positioning means includes means for endwise oifsetting of selected sheets on said arms.

10. A device as in claim 8, together with means for laterally shifting said arms, thereby to laterally offset selected sheets stacked thereon.

11. A device as in claim 8, together with a conveyor positioned to receive stacked sheets from said supporting arms as the latter move into said lowered position thereof, together with temporary supporting arms movable into position adjacent said rolls for receiving sheets while said first arms are in said lowered position.

12. A material stacking device as set forth in claim 8, wherein said release means comprise means for raising said magnet means relative to said rolls to release the sheet material.

13. A device for stacking sheet material comprising at least two rolls adapted to receive sheet material against the underside thereof, means for delivering successive sheets of material along the underside of said rolls in a direction generally normal to the axes thereof, means for holding successive sheets of material against the underside of said rolls as the material is delivered therealong and then releasing the same, means for supporting the released sheets, and means movable against the trailing end of the released sheets for endwise positioning thereof, said lastnamed means including a table on which the trailing end portion of a released sheet is temporarily supported, and pusher means engaging the trailing end of such a temporarily supported sheet and pushing the same off one end of said table, said one table end thereby defining an end position for the sheet material being stacked.

14. A device for stacking magnetic sheet material as set forth in claim 13, together with means urging said rolls in a direction of rotation opposing the direction of delivery of a sheet therealong, thereby to slow down and stop sheet material delivered along the underside of said rolls.

15. A sheet material stacking device as set forth in claim 13, wherein there are at least two such pusher means arranged for alternate operation.

16. A sheet material stacking device as set forth in claim 13, together with means for shifting the position of said one table end, thereby to longitudinally offset selected sheets in a stack thereof.

17. A sheet material stacking device as set forth in claim 13, wherein said pusher means include a pusher dog pivotally supported for movement between a raised position projecting above said table for engaging the trailing end of a sheet supported thereon and a lowered position out of contact with such sheet, a drive motor for extending and retracting said pusher dog, and means connecting said drive motor to said dog for automatically shifting the latter into said raised position While said dog is being extended and into said lowered position while said dog is being retracted.

18. A device for stacking sheet material comprising a conveyor having at least two rolls adapted to receive a sheet of material against the underside thereof, means for delivering successive sheets of material along the underside of said rolls in a direction generally normal to the axes thereof, means releasably holding successive sheets of material against the underside of said rolls as the sheets are delivered therealong, and drive means urging at least certain of said rolls in a rotational direction opposing the travel of sheet material along the underside thereof, thereby to slow down and stop sheet material delivered along the underside of said rolls, wherein said drive means comprise an endless drive member in frictional contact with the upper surfaces of said rolls for rotating the same, and plural individual weight members superposed on said endless drive member and pressing the latter against said rolls for increasing the frictional contact between said drive member and said rolls.

References Cited UNITED STATES PATENTS 1,444,999 2/1923 Bennett et a1 214-6 1,756,118 4/1930 Genenger 193-35 2,015,809 10/1935 Moore 2146 2,389,107 11/1945 Rice.

2,397,720 4/ 1946 Beane 214-6 2,492,889 12/ 1949 Royal.

2,566,240 8/1951 Mursch.

2,626,800 1/ 1953 Martin.

2,893,573 7/1959 Buccicone 214-6 2,895,733 7/1959 Powers 271-18 2,918,852 12/1959 Buccicone.

2,976,075 4/1961 Budreck 29465.5 2,985,322 5/1961 Parker 214-6 3,273,726 9/ 1966 Buccicone 214-6 GERALD M. FORLENZA, Primary Examiner. J. E. OLDS, Assistant Examiner. 

1. A DEVICE FOR STACKING SHEETS OF MAGNETIC MATERIAL COMPRISING A SERIES OF ROLLS ADAPTED TO RECEIVE SUCCESSIVE SHEETS THEREALONG AGAINST THE UNDERSIDE THEREOF, MEANS FOR DELIVERING SUCCESSIVE SHEETS OF MAGNETIC MATERIAL ALONG SAID SERIES OF ROLLS ON THE UNDERSIDE THEREOF IN A DIRECTION GENERALLY NORMAL TO THE AXES OF ROTATION OF SAID ROLLS, MAGNET MEANS POSITIONED BETWEEN ADJACENT ONES OF SAID ROLLS AND OPERABLE TO HOLD MAGNETIC SHEET MATERIAL AGAINST SAID ROLLS THROUGH MAGNETIC ATTRACTION OF THE SHEET TO THE MAGNET MEANS INDEPENDENT OF THE ROLLS, AND MEANS FOR RAISING SAID MAGNET MEANS RELATIVE TO SAID ROLLS FOR RELEASING A SHEET FROM THE MAGNETIC HOLD OF SAID MAGNET MEANS TO DROP FROM SAID SERIES OF ROLLS WHEREIN SAID MAGNET MEANS ARE MAINTAINED OUT OF PHYSICAL CONTACT WITH A SHEET HELD AGAINST THE UNDERSIDE OF SAID ROLLS. 